§ 18
How large should the return hose be for 40 l/min?
Answer: A hose or tube that's too small gives too high velocity in the oil, pressure drop, heat and noise. The hose producers' nomogram connects flow, velocity and inner diameter. The calculator does the same with calculation: you enter the flow and choose the line type, and it gives the smallest inner diameter, the next hose size (SAE dash number in 1/16 inch) and the velocity in that hose. You choose the pressure class based on the system's maximum pressure.
Flow i m³/s = l/min ÷ 60.000
Areal A = Q ÷ v, og diameter d = √(4 × A ÷ π)
Dash-nummeret er den indvendige diameter i sekstendedele tomme: −8 = 8/16" = 12,7 mm. Størrelserne her er −4, −5, −6, −8, −10, −12, −16, −20, −24, −32, −40 og −48
Maximum speeds are Parker's recommendations for hydraulic hoses: 4 ft/s suction, 10 ft/s return, 25 ft/s pressure
| Symbol | Meaning | Unit |
|---|---|---|
| flow_lmin | Flow in the pipe | l/min |
| hastighed | Cable type (recommended max. speed) | — |
| = | Hose size (SAE dash No., 1/16 inch) | — |
| = | Minimum inside diameter | mm |
| = | Internal diameter for this hose size | mm |
| = | Velocity in that hose | m/s |
Does not apply when
The calculator's own default values inserted. The figures are calculated with exactly the formula the tool uses.
Substituted
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Når du monterer eller skifter slanger på en lift, kran eller tip, skal den indvendige diameter passe til flowet. Beregneren giver mindste diameter, slangestørrelse og hastighed.
En returledning skal føre 40 l/min tilbage til tanken.
It means: Mindste diameter er 16.8 mm, så du skal bruge dash 12 med 19 mm indvendigt. Hastigheden bliver 2.34 m/s.
Samme flow i trykledningen.
It means: Trykledningen kan være dash 8, og hastigheden bliver 5.26 m/s.
Samme flow på pumpens sugeside.
It means: Sugeledningen skal være dash 20, med hastigheden 0.84 m/s.
Sugeledningen skal være størst, trykledningen mindst.
Hastigheden i den valgte slange skal være under grænsen.